Traditional, effective springpowered traps need manual loading after every operation, with the traps severally requiring removal of the executed rat, renewal of the bait in the trap, and retightening of the executing member. For large scale rat control, for example, with respect to sewage rats, the above mentioned traps are hopelessly inapplicable, therefore in practice, control is attempted by laying down of rat poison. This often takes place in precarious environments, for example, at or in the immediate vicinity of food manufacturing companies, which is not very ideal.
Ideally an effective extermination should only be effected by the use of mechanically operated traps, but these must then be operable several or many times without necessitating reqular supervision. Traps of this type have already been proposed in, see for example, U.S. Pat. No. 4,554,524, but for various reasons have not gained any acceptance in practice. The proposed traps suffer from so many disadvantages that they are in fact unusable in as much as detection of a rat is extremely uncertain as a rat must actuate a detector or member in a specific direction, removal of the rats after each execution is limited to collecting them in a drawer or container beneath the trap, which, in practice, means a great restriction of the possibilities for the gathering or removal of large numbers of exterminated rats, execution of the rats takes place by a transverse movement of a transverse brace against a sideplate portion of the trap, whereby execution of the rats can very well be connected with an injury and an associated undesirable release of blood, and totally unacceptable pains for the animal, as it will be entirely coincidental where the transverse-brace hits the body of the animal, and only a small number of rats can be executed between each supervision of the trap, since the bait used can be eaten by the first rat to visit the trap.
There have been other proposals such as in, for example, U.S. Pat. No. 3,638,348 and WO 82/00568, where even more disadvantages have been encountered, not the least regarding the removal of the previously executed rats so that there after each or only very few activations there is barely room for the entrance of more rats into the trap, an similarly the method of execution is coincidental and extremely brutal.